Sensory neurons in the human jugular ganglion.

The jugular ganglion (JG) contains sensory neurons of the vagus nerve which innervate somatic and visceral structures in cranial and cervical regions. In this study, the number of sensory neurons in the human JG was investigated. And, the morphology of sensory neurons in the human JG and nodose ganglion (NG) was compared. The estimated number of JG neurons was 2721.8-9301.1 (average number of sensory neurons ±â€¯S.D. = 7975.1 ±â€¯3312.8). There was no significant difference in sizes of the neuronal cell body and nucleus within the JG (cell body, 1128.8 ±â€¯99.7 µâ€¯m2; nucleus, 127.7 ±â€¯20.8 µâ€¯m2) and NG (cell body, 963.8 ±â€¯225.7 µâ€¯m2; nucleus, 123.2 ±â€¯32.3 µâ€¯m2). These findings indicate that most of sensory neurons show the similar morphology in the JG and NG. Our immunohistochemical method also demonstrated the distribution of ion channels, neurotransmitter agents and calcium-binding proteins in the human JG. Numerous JG neurons were immunoreactive for transient receptor potential cation channel subfamily V member 1 (TRPV1, mean ±â€¯SD = 19.9 ±â€¯11.5 %) and calcitonin gene-related peptide (CGRP, 28.4 ±â€¯6.7 %). A moderate number of JG neurons contained TRPV2 (12.0 ±â€¯4.7 %), substance P (SP, 15.7 ±â€¯6.9 %) and secreted protein, acidic and rich in cysteine-like 1 (SPARCL1, 14.6 ±â€¯7.4 %). A few JG neurons had vesicular glutamate transporter 2 (VGLUT2, 5.6 ±â€¯2.9 %) and parvalbumin (PV, 2.3 ±â€¯1.4 %). SP- and TRPV2-containing JG neurons had mainly small and medium-sized cell bodies, respectively. TRPV1- and VGLUT2- containing JG neurons were small to medium-sized. CGRP- and SPARCL1-containing JG neurons were of various cell body sizes. Sensory neurons in the human JG were mostly free of vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH) and neuropeptide Y (NPY). In the external auditory canal skin, subepithelial nerve fibers contained TRPV1, TRPV2, SP, CGRP and VGLUT2. Perivascular nerve fibers also had TRPV1, TRPV2, SP, CGRP, VIP, NPY and TH. However, PV- and SPARCL1-containing nerve endings could not be seen in the external auditory canal. It is likely that sensory neurons in the human JG can transduce nociceptive and mechanoreceptive information from the external auditory canal. Theses neurons may be also associated with neurogenic inflammation in the external auditory canal and ear-cough reflex through the vagus nerve.

3D fiber deposited polymeric scaffolds for external auditory canal wall.

The external auditory canal (EAC) is an osseocartilaginous structure extending from the auricle to the eardrum, which can be affected by congenital, inflammatory, and neoplastic diseases, thus reconstructive materials are needed. Current biomaterial-based approaches for the surgical reconstruction of EAC posterior wall still suffer from resorption (biological) and extrusion (synthetic). In this study, 3D fiber deposited scaffolds based on poly(ethylene oxide terephthalate)/poly(butylene terephthalate) were designed and fabricated to replace the EAC wall. Fiber diameter and scaffold porosity were optimized, leading to 200 ± 33 µm and 55% ± 5%, respectively. The mechanical properties were evaluated, resulting in a Young's modulus of 25.1 ± 7.0 MPa. Finally, the EAC scaffolds were tested in vitro with osteo-differentiated human mesenchymal stromal cells (hMSCs) with different seeding methods to produce homogeneously colonized replacements of interest for otologic surgery. This study demonstrated the fabrication feasibility of EAC wall scaffolds aimed to match several important requirements for biomaterial application to the ear under the Tissue Engineering paradigm, including shape, porosity, surface area, mechanical properties and favorable in vitro interaction with osteoinduced hMSCs. This study demonstrated the fabrication feasibility of outer ear canal wall scaffolds via additive manufacturing. Aimed to match several important requirements for biomaterial application to ear replacements under the Tissue Engineering paradigm, including shape, porosity and pore size, surface area, mechanical properties and favorable in vitro interaction with osteo-differentiated mesenchymal stromal cells.

Exposure to non-ionizing electromagnetic fields emitted from mobile phones induced DNA damage in human ear canal hair follicle cells.

The aim of this study was to investigate effect of radiofrequency radiation (RFR) emitted from mobile phones on DNA damage in follicle cells of hair in the ear canal. The study was carried out on 56 men (age range: 30-60 years old)in four treatment groups with n = 14 in each group. The groups were defined as follows: people who did not use a mobile phone (Control), people use mobile phones for 0-30 min/day (second group), people use mobile phones for 30-60 min/day (third group) and people use mobile phones for more than 60 min/day (fourth group). Ear canal hair follicle cells taken from the subjects were analyzed by the Comet Assay to determine DNA damages. The Comet Assay parameters measured were head length, tail length, comet length, percentage of head DNA, tail DNA percentage, tail moment, and Olive tail moment. Results of the study showed that DNA damage indicators were higher in the RFR exposure groups than in the control subjects. In addition, DNA damage increased with the daily duration of exposure. In conclusion, RFR emitted from mobile phones has a potential to produce DNA damage in follicle cells of hair in the ear canal. Therefore, mobile phone users have to pay more attention when using wireless phones.

Comparison of changes in mitochondrial bioenergetics between keratinocytes in human external auditory canal skin and cholesteatomas from normoxia to hypoxia.

Cholesteatoma has attracted many studies seeking to uncover its nature and the pathogenesis of related diseases. However, no researchers have explored the mitochondrial bioenergetics of cholesteatoma. The aim of this study was to investigate the energy demand and differential mitochondrial respiration profiles between keratinocytes in external auditory canal (EAC) skin and cholesteatoma samples cultured in normoxic (20% O2) and hypoxic (5% O2) conditions. Enhanced cellular proliferation of both types of keratinocytes was found in hypoxia compared to normoxia. In 20% O2 conditions, cholesteatoma keratinocytes exhibited less mitochondrial mass, lower ATP levels, and significantly lower basal oxygen consumption rate (OCR) and reserve capacity compared to normal skin keratinocytes. In contrast, in hypoxic conditions, cholesteatoma keratinocytes showed markedly higher levels in maximal OCR and reserve capacity, as well as lower proton leak OCRs, compared to normal skin keratinocytes. Hypoxia induced the reverse mitochondrial bioenergy profile from that in normoxia between these two types of keratinocytes, implying that an adaptive change of mitochondrial respiration to oxygen fluctuations may develop in cases of cholesteatoma. Such adaptation in response to hypoxic conditions may play a role in explaining the pathogenesis of acquired cholesteatoma.

Impression Smear Agreement with Acetate Tape Preparation for Cytologic Sampling.

Cutaneous cytologic sampling techniques are used to detect bacteria, yeast, and inflammatory cells for diagnosis and therapeutic monitoring. Studies have examined slide evaluation techniques, ear swab cytology staining methods, and observer variations; few studies compare common clinical sampling techniques. The primary aim of this study was to measure detection of microorganisms and neutrophils by impression smear compared to acetate tape preparation; comparison of agreement between two acetate tape staining methods was a secondary aim. Thirty lesions consistent with superficial pyoderma were sampled via impression smear and acetate tape preparation. Acetate tape preparations were either stained with modified Romanowksy stain solutions two and three or solution three alone. Impression smears were stained in the standard manner. Bacteria, yeast, and neutrophils were evaluated using a semi-quantitative scale [0-4]. Quantities were aggregated and compared using Cohen's kappa to measure agreement between methods. When impression smears were compared to acetate tape, the lowest agreement occurred for neutrophils, with impression smears detecting more neutrophils. Comparison of acetate tape staining methods had the highest agreement for yeast detection. Sampling technique and staining method did not differ for detection of bacteria. Impression smears detected more neutrophils, and yeast detection appeared equivalent for acetate tape staining methods.

Fetal development and variations in the cartilages surrounding the human external acoustic meatus.

In contrast to the osseus part that develops from the tympanic ring of the squamous part of the temporal bone after birth, there is little information on fetal development of the cartilages surrounding the human external acoustic meatus. Using routine histology and immunohistochemistry, we examine sections of 22 fetuses (CRL 100-270mm) to study the development of these cartilages. Early external ear cartilages are composed of three groups: (1) a ring-like cartilage at the putative tragus on the anterior side of the meatus, (2) two or three bar-like cartilages along the inferior wall of the meatus, and (3) a plate-like cartilage in a skin fold for the putative helix on the posterior side. In contrast to the first and second pharyngeal arch cartilages, all the external ear cartilages express glial fibrillary acidic protein. Notably, the bar-like cartilages along the meatus are connected with a fascia-like structure to the second pharyngeal arch cartilage. Later, with considerable individual variation, new cartilage bars extend from the inferior cartilages to the superior side of the meatus. Thus, via an intermediate stage showing a chain of triangular elastic cartilages, a chain of bar-like cartilages on the inferior side appears to change into a complex of H-shaped cartilages. Numerous ceruminous glands are seen in the thick subcutaneous tissue overlying the cartilaginous part of the meatus. However, they do not insert into the cartilage. The external ear cartilages develop much earlier than, and independently of, the osseus part.

Spatial distribution of antimicrobial peptides and mast cells in the skin of the external auditory canal.

OBJECTIVE: The direct activity of antimicrobial peptides against microbes is thought to be an essential first line of defence in the skin; however, little is known about antimicrobial peptide secretion in the skin of the external auditory canal. Evidence suggests that mast cells contribute to the secretion of antimicrobial peptides. This study aimed to examine the distribution of mast cells and antimicrobial peptides, including human ß-defensin-1 and -2 and LL-37, in the external auditory canal skin. METHODS: External auditory canal skin samples from 12 patients undergoing middle-ear surgery with canaloplasty were immunohistochemically stained to detect expression of mast cell markers (tryptase and chymase) and antimicrobial peptides (human ß-defensin-1 and -2 and LL-37). RESULTS: Mast cells and human ß-defensin-1 were present in the ceruminous glands but not in the sebaceous glands. The increased presence of mast cells, human ß-defensin-1 and LL-37 in ceruminous glands suggests that mast cells may participate in the secretion of antimicrobial peptides from ceruminous glands. CONCLUSION: These findings suggest that mast cells contribute to the secretion of antimicrobial peptides in the ceruminous glands of the external auditory canal skin.

Up-regulation of neutrophil gelatinase-associated lipocalin in cholesteatoma.

CONCLUSION: Neutrophil gelatinase-associated lipocalin (NGAL) and Ki-67 expression were up-regulated in cholesteatoma and the expression pattern of NGAL in the epithelial layer was inversely related to the expression of Ki-67. Therefore, NGAL may be related to dysregulated differentiation in the keratinocytes during the development of a cholesteatoma. OBJECTIVES: We investigated the differential expression and localization of NGAL in middle ear cholesteatoma and compared the results to normal external auditory canal (EAC) skin. We also compared the expression and localization of NGAL with the expression and localization of Ki-67 in middle ear cholesteatoma. SUBJECTS AND METHODS: Tissue samples from middle ear cholesteatomas and normal EAC skin were obtained from 20 patients undergoing middle ear surgery. NGAL mRNA expression was determined by the reverse transcriptase-polymerase chain reaction (RT-PCR). The expression of NGAL protein was analyzed by Western blot. NGAL and Ki-67 were localized by immunohistochemical staining. RESULTS: A significantly greater expression of the NGAL mRNA was observed in cholesteatoma epithelium than in normal EAC skin (p < 0.05). NGAL was detected in the granular layer of cholesteatoma. However, NGAL was scarcely expressed in normal EAC skin. Ki-67 was detected predominantly in the basal and parabasal layers of cholesteatoma epithelium.

Malassezia otitis externa in the dog: the effect of heat-fixing otic exudate for cytological analysis.

This study was conducted on 32 dogs with Malassezia otitis externa to determine the effect of heat-fixing otic exudate on cytological analysis. Malassezia infection was confirmed by cytological examination of otic exudate. Otic discharge collected with cotton swabs was then rolled onto glass slides. One slide per dog was heat-fixed prior to staining; the other slide was not heat-fixed. The number of yeast in 10 oil-immersion fields (1000 x magnification) was counted for both slides from each dog. Heat-fixing did not systematically cause either increased or decreased numbers of Malassezia on cytology of otic exudate.

Ear canal keratinocyte culture: clinical perspective.

HYPOTHESIS: Autologous epidermal sheets obtained by cultivating keratinocytes of the external auditory meatus can be used to repair cutaneous defects of the ear canal. The Rheinwald and Green method has been used to know whether the produced epidermal layer preserves its specificities after the culture. BACKGROUND: Using a split-thickness skin graft during a functional ear atresia surgery does not allow for the restitution of external auditory canal self-cleaning. Some authors cultivated external auditory meatus keratinocytes and showed migration capacities of these colonies. METHODS: Samples of preauricular skin and of the bony part of the external auditory canal were harvested from 10 patients. Keratinocytes were extracted and cultured until an epidermal sheet was obtained. The output, the keratinocyte plating efficiency, and the production delay were measured during the culture. Culture product sections and biopsy sections were examined using optical microscopy after standard coloration and indirect immunohistochemistry. RESULTS: Nine epidermal layers from 10 biopsies were obtained in each group. A significant difference between external auditory meatus and preauricular keratinocyte plating efficiency was highlighted. The average production delay of 23 cm2 external auditory canal and preauricular epidermal layers was 21 days. There was no difference in the cytokeratine expression between external auditory canal and preauricular skin, nor between external auditory canal and preauricular culture products. All cultures expressed the cytokeratine 5 characteristic of stratifying epithelium. CONCLUSION: The Rheinwald and Green keratinocyte culture method allows the production of ear canal-stratified epidermal sheets, which can be used for external ear reconstruction.

Comparison of 4 fixation and staining methods for the cytologic evaluation of ear canals with clinical evidence of ceruminous otitis externa.

BACKGROUND: Swab cytology of ear canals is one of the most useful and rapid methods to assess the presence of external ear infections. Smears are generally stained with rapid Romanowsky-type stains, with or without prior heat fixation. OBJECTIVES: The aim of this study was to compare 4 different methods of fixation and staining of ear swab cytology samples from dogs. METHODS: Eight dogs with otitis externa were selected from a dermatology referral population. A cotton swab was used to obtain ceruminous material from 12 ear canals. Four smears of each swab were prepared on glass slides (randomly identified as A, B, C, or D) and air-dried for cytologic examination. Samples marked A were stained with Dip Quick (Jorgensen Laboratories Inc, Loveland, CO, USA) after heat fixation; samples marked B were stained without heat fixation; samples marked C were heat-fixed and dipped only in the counterstain (the blue reagent) of Dip Quick; and samples marked D were dipped only in the counterstain, without heat fixation. Ten high-power fields (hpf; X100 oil immersion objective) in each slide were evaluated by 2 observers, and total numbers of keratinocytes, yeast, bacteria, and neutrophils were counted. Statistical comparison was performed using an ANOVA model applied after verifying the normal distribution of the data, and using nonparametric sign tests and Wilcoxon signed rank tests. RESULTS: No statistically significant differences were observed in the numbers of keratinocytes, yeast, bacteria, or neutrophils among the 4 staining methods (P > .05), although significant interobserver differences were found. CONCLUSION: We conclude that heat fixation does not improve the quality of ceruminous ear swab samples for cytologic evaluation, and propose a 1-step dip in the blue reagent alone as a rapid method of staining samples from canine ear canals.

Otoscopic, cytological, and microbiological examination of the equine external ear canal.

Otoscopic examination and cytology of the equine ear would be beneficial in diseases such as head trauma, headshaking, otitis externa secondary to otitis media, vestibular disease, aural neoplasia and aural pruritus secondary to parasites. In practice, otic examinations of horses are rarely done due to the perceived difficulty in visualizing the equine external ear canal and tympanic membrane, as well as the need for chemical restraint. In this study, the proximal external ear canal was examined in live horses using a handheld otoscope and in cadaver heads using video otoscopy. Visualization of the proximal ear canal of the sedated horse could be done with a handheld otoscope, but more sedation or general anaesthesia and a video otoscope would be required to adequately visualize the tympanic membrane in the live horse. The proximal ear canals of 18 horses were examined cytologically and cultured aerobically. In three horses, both ears were sampled. No cells or organisms were seen on cytological examination of 11/21 ears. Nine of the 21 ears were sterile when cultured. Ten of the 21 ears had mixed growth with low numbers of organisms (Corynebacterium sp. being most common). Two of the 21 ears had heavy growth of a single organism (Corynebacterium sp. and Staphylococcus intermedius, respectively). Equine cadaver heads were examined in cross-section by computed tomography (CT) imaging and histopathology in order to further understand the anatomy of the equine external ear canal. Equine practitioners should be aware that otic examination is possible and may provide important diagnostic information.

Toll-like receptors 2, 3 and 4 (TLR-2, TLR-3 and TLR-4) are expressed in the microenvironment of human acquired cholesteatoma.

Human toll-like receptors (TLR 1-10) are crucial in the induction and activation of innate immunity in the course of an infection. They are expressed mainly on the cells of the immune system, and also on some epithelia and endothelia. Their ligands so called pathogen associated molecular patterns are abundant on invading microbes. TLR-ligand binding results in cell signal transduction and subsequent production of various proinflammatory cytokines such as IL-1 and TNF-alpha. Acquired cholesteatoma is formed during chronic otitis media in the proportion of cases. It has adverse effects on ear structures, resulting in osteolysis and bone resorption. Its formation and pathogenesis are not fully understood. The current study attempted to search the possible role of TLRs in this somewhat awkward pathological condition. Surgical specimens of human acquired cholesteatoma (n=15) and normal external auditory canal skin (n=5, control tissues) were tested by immunohistochemistry for the presence of TLRs. Three TLRs were examined: TLR-2, TLR-3 and TLR-4. All TLRs tested were demonstrated in matrix (layer of keratinizing epithelium) and perimatrix (granulation tissue) of this inflammatory tumour. Expression of particular TLRs within the keratinizing epithelium was distinct and uneven. In the perimatrix, numerous T (CD3+) cells were seen and relatively few macrophages (CD11c+, HLA-DR+). There was a weak expression of all TLRs on normal (non-inflammatory) skin. Expression of TLR-3 both on the epithelium and some cells within the perimatrix and the presence of T cells may suggest that apart from innate immune responses, mechanisms of adaptive immunity also operate in cholesteatoma. Weak expression of these receptors on normal skin may also suggest the important role of TLRs in the etiopathogenesis of cholesteatoma.

Mitochondrial apoptotic pathways

Apoptosis or programmed cell death (PCD) is a physiological process characteristic of pluricellular organisms leading to self-destruction of the cell. It is therefore involved in development, homeostasis and host defense. However, a significant difference has been shown between mammalian cell apoptosis and non-mammalian cell apoptosis: mitochondria are implicated only in the former. Execution of PCD includes the release of several proapoptotic proteins from the intermembrane space of mitochondria. They could exert their actions through a caspase dependent as well as a caspase independent way. On the other hand, regulation of PCD is mainly given by the Bcl-2 family members, which are in turn essentially regulated by activation of death receptors and/or DNA damage. Nowadays, execution of apoptosis is better known than its regulation. Nevertheless, we are still far of a complete understanding of the apoptotic process

Mitochondrial apoptotic pathways

Apoptosis or programmed cell death (PCD) is a physiological process characteristic of pluricellular organisms leading to self-destruction of the cell. It is therefore involved in development, homeostasis and host defense. However, a significant difference has been shown between mammalian cell apoptosis and non-mammalian cell apoptosis: mitochondria are implicated only in the former. Execution of PCD includes the release of several proapoptotic proteins from the intermembrane space of mitochondria. They could exert their actions through a caspase dependent as well as a caspase independent way. On the other hand, regulation of PCD is mainly given by the Bcl-2 family members, which are in turn essentially regulated by activation of death receptors and/or DNA damage. Nowadays, execution of apoptosis is better known than its regulation. Nevertheless, we are still far of a complete understanding of the apoptotic process

[Expression of hypoxia-inducible factor-1alpha in middle ear cholesteatoma].

OBJECTIVE: To explore the pathogenetic mechanism of middle ear cholesteatoma, the aim of this study is to detect the expression of Hypoxia-inducible factor-1alpha in middle ear cholesteatoma and normal external ear canal skin. METHOD: We used the technology of immunohistochemistry to examine the expression of Hypoxia-inducible factor-1alpha in thirty-one middle ear cholesteatomas and ten samples of normal external ear canal skin. RESULT: The expression of HIF-1alpha was extremely higher in middle ear cholesteatomas than in normal external ear canal skin (P <0.05). CONCLUSION: We found that the higher expression of Hypoxia-inducible factor-1alpha in middle ear cholesteatomas, so we think that Hypoxia-inducible factor-1alpha play an important role in the pathogenetic process of middle ear cholesteatoma, and hypoxia may be an incentive in the pathogenetic mechanism of middle ear cholesteatoma.

Effect of 17 beta-estradiol on diastrophic dysplasia sulfate transporter activity in otosclerotic bone cell cultures and SaOS-2 cells.

OBJECTIVE: Diastrophic dysplasia sulfate transporter (DTDST) is involved in the regulation of bone turnover, and its activity in otosclerosis has been shown to be abnormally high. Taking into account the role of estrogens in the progression of otosclerosis, the possible effect of estrogens on DTDST was investigated in otosclerotic bone cell cultures and in SaOS-2, a human osteoblastic cell line. MATERIAL AND METHODS: Primary bone cell cultures of stapes and external auditory canal (EAC) bone were obtained from 33 patients with otosclerosis and 18 control patients undergoing cerebellopontine angle tumor surgery. These cultures were assessed in parallel with SaOS-2 cells. Estrogen receptors (ERs) were detected using reverse transcriptase polymerase chain reaction. DTDST activity was assessed by sulfate uptake at baseline and after 24 h of incubation with 17 beta-estradiol at concentrations ranging from 10(-12) to 10(-6) M. RESULTS: Stapes and EAC cultures predominantly expressed mRNA of ER alpha, while ER beta expression was predominant in SaOS-2 cells. In stapes and EAC cultures no modification of DTDST activity was observed with 10(-8) M 17 beta-estradiol. In SaOS-2 cells, DTDST activity was inhibited by 17 beta-estradiol (93.5+/-9.21 vs 83.6+/-8.83 pmol/mg protein/5 min, n=29; mean of differences=10.0+/-3.22, paired t-test, p<0.01). CONCLUSION: DTDST activity is regulated by estrogens in SaOS-2 cells, but not in primary cell cultures from stapes and EAC. This difference in the regulation mechanisms may be related to the type of estrogen receptor expressed.

Otic cytology in health and disease.

Accurate characterization of the primary cause and perpetuating factors is essential for successful management of ear disease in dogs and cats. Cytology is a simple, rapid, and practical diagnostic test that should be performed routinely on any and all patients presented for clinical signs consistent with otitis externa. In combination with clinical signs, otoscopic evaluation, and diagnostic testing of primary disease, serial cytology enhances the ability of veterinarians to diagnose secondary infections, monitor progression of disease, evaluate response to therapy, and make appropriate management decisions. Cytologic specimens should be evaluated for the presence, numbers, and characteristics of three key features: yeast, bacteria, and leukocytes. More than five yeast organisms or more than 25 bacteria per high-powered field is suggestive of significant microbial activity warranting therapeutic intervention. The presence of leukocytes, particularly with phagocytized bacteria, indicates "true infection" rather than overgrowth; if suppurative discharge is present, systemic therapy is needed. Cytology combined with culture and susceptibility is the best method for identification of bacterial overgrowth and infection; however, if only one test can be performed, always choose cytology. Culture results assist in the selection of appropriate antibiotic therapy, but cytology determines whether systemic antibiotics are indicated, which organisms are most significant, and when therapy can be discontinued.

Canal wall reconstruction with Mimix hydroxyapatite cement: results in an animal model and case study.

OBJECTIVE/HYPOTHESIS: To assess Mimix hydroxyapatite cement for its applicability in canal wall reconstruction using the gerbil as a canal wall model. A case is presented to illustrate a novel technique of canal wall reconstruction using Mimix on the basis of the findings of our animal research. STUDY DESIGN: This was a preclinical study. METHODS: Ten Mongolian gerbils were implanted with Mimix, with the left side used to simulate mastoid obliteration and the right side used to simulate canal wall reconstruction. Pre- and postsurgery auditory-evoked brainstem responses were used to assess ototoxicity, and hematoxylin-eosin staining of histologic sections was used to assess inflammatory and foreign-body response and new bone formation. RESULTS: Rapid wound healing was achieved with each of the nine animals evaluated, with no erythema, edema, or drainage. Inspection of the ear canal at the time of sacrifice revealed no signs of otitis media and no middle ear effusions. Microscopic examination showed no inflammatory response or foreign-body reaction, good mucosalization on the side of the implant facing the bulla, and minimal fibrosis adjacent to the skin. Eight of nine specimens showed new woven bone ingrowth at the bone implant interface, with active osteoblasts and viable lacunae cells. There were no apparent fractures in the implanted material. CONCLUSIONS: Mimix hydroxyapatite cement is biocompatible and suitable for canal wall reconstruction in the animal model. The characteristics of this cement, namely its ability to set quickly in a moist environment, offer advantages over previously used cements for canal wall reconstruction.

Increased activity of the diastrophic dysplasia sulfate transporter in otosclerosis and its inhibition by sodium fluoride.

HYPOTHESIS: This study investigates the function of the diastrophic dysplasia sulfate transporter (DTDST) in otosclerotic bone and the effect on it of sodium fluoride (NaF). BACKGROUND: Otosclerosis is a localized bone dystrophy with increased bone turnover. DTDST is implicated in the regulation of the bone turnover. MATERIALS AND METHODS: Primary cultures of cells were obtained from the stapes and external auditory canal (EAC) of 26 patients with otosclerosis and from nine control patients. Sulfate uptake was quantified under basal conditions and with NaF. The NaF signaling pathways were investigated using forskolin and verapamil. RESULTS: The relative initial rates of sulfate uptake and the apparent Vmax values were: otosclerotic stapes > EAC > control stapes = control EAC. The sulfate uptake by the otosclerotic stapes was correlated with the loss of sensorineural hearing. The amounts of DTDST mRNA (RNase protection assay) in the four subgroups did not differ. NaF (10(-6)M, 1 hr) inhibited sulfate uptake by the otosclerotic stapes and EAC cells but not by control samples. CONCLUSION: The authors believe that whether the increased DTDST activity is a cause or an effect of otosclerosis, it appears to be a specific target for NaF treatment.